| Co-Investigator(Kenkyū-buntansha) |
D.J. Crawfor オハイオ州立大学, 植物学教室, 教授
ITO Motomi Research Associate ; Faculty of Science, Tokyo Metropolitan University, 理学部, 助手 (00193524)
CRAWFORD Daniel j. Professor ; Department of Botany, Ohio State University
KING R. スミソニアン研究所, 研究員
CRAWFORD D.J オハイオ州立大学, 植物学教室, 教授
渡辺 邦秋 神戸大学, 教養部, 教授 (80031376)
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| Budget Amount *help |
¥8,500,000 (Direct Cost: ¥8,500,000)
Fiscal Year 1992: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1991: ¥7,000,000 (Direct Cost: ¥7,000,000)
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| Research Abstract |
In Eupatorieae, n=10 is prevailing and has been considered to be a basic chromosome number. However, some genera have n=15,16,17 and 25. Based on evidence of extensive gene duplications in Eupatorium with n=10,Yahara et al (1991) postulated that the tribe is of polyploid origin and n=10 is derived from larger chromosome numbers. To test this hypothesis, We carried out molecular systematic study on genera with n=9,10,11,17, and 25.
To obtain plant materials for molecular systematic studies, we carried out field works in Texas and Costa Rica. Total DNAs were isolated from these materials and RFLPs were detected using probes of lettuce chloroplast DNA. Clibadium and Coreopsis of Heliantheae were used as outgroups to construct a cladogram.
As a result of cladistic on RFLP data sets, it is shown that two clades were diverged after the origin of the Eupatorieae ; one including Ageratina (n=17) and Neomirandia (n=17,25), and the other including Mikania (n=16-18),Stevia (n=11), eight genera with n=10, and Brickellia (n=9). This result supports the hypothesis that n=10 is derived from larger chromosome numbers. It is already shown from cpDNA data that Eupatorieae is derived from Heliantheae. In Heliantheae, it has been suggested that genera with n=16 in Heliantheae are derived from ancestral genera with n=8. The result of this study suggests that Eupatorieae isderived from species with n=16 in Heliantheae. In Eupatorieae, some Mexican genera have been known to have n=16. Materials of one of those genera, Bartlettina, have been recently obtained and molecular systematic analysis of this genus is now ongoing.
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